Chicago Cubs righthander Matt Garza has been diagnosed with a mild lat strain on his left side and will be shut down for at least a week, the team’s website reports.

Garza made it only 20 pitches into a planned 40-pitch bullpen session Sunday after experiencing discomfort in his side.

"It's safe to say it pushes back his first (Cactus League) start, and what it means for the regular season, it's clearly much too early to say," general manager Jed Hoyer told the website. "We felt (the MRI results were) really good news. It is a mild strain, and we do think it'll be about a week until he should be pain-free, based on the MRI.”

The injury might delay Garza’s regular season debut, but it basically assures he will begin the season with the Cubs. Garza was shopped last summer before he suffered a season-ending elbow injury in July.

The 29-year-old went 5-7 with a 3.91 ERA and 96 strikeouts in 18 starts (103 2/3 innings) last season.

The Cubs also recently announced that starter Scott Baker, who is recovering from Tommy John surgery, likely will begin the regular season on the disabled list.